1. Field of the Invention
This invention relates to tissue processing methods and more specifically to a method of processing tissue for light microscopy examination.
2. Description of the Prior Art
The processing of tissue for both electron and light microscopy examination has been the subject of step-by-step improvement. Automatic processing of tissue for electron microscopy tissue processing has been achieved as exemplified in applicant's U.S. Pat Nos. 3,526,203 and 3,771,490.
Automated processing of tissue for light microscopy examination has been achieved as exemplified in the method used in the so-called "Technicon" tissue processor; however, there has been no successful method which would allow light microscopy tissues to be processed in a completely automatic sequence, while being held in an entirely closed system and without requiring substantial movement of the specimens. The availability of a method of processing in a closed system is of critical importance in view of recently published Federal regulations governing handling of hazardous vapors and fumes.
Representative prior art includes U.S. Pat. Nos. 3,227,130; 2,959,151; 2,386,079; 2,341,198; 2,157,875; 2,959,151; 3,400,726; 2,681,298; and 2,684,925.
A review of the prior art further reveals that treating fluids in light microscopy processors are normally required to be recirculated. The processing fluids may be manually returned to their respective containers after use. Processing takes place in open or loosely covered chambers which are not suitable for holding pressure or vacuum conditions. Many of the prior art light microscopy processors, e.g., the so-called "Technicon" tissue processor, also depend upon substantial movement and dipping motions of the tissue specimens into open containers. Any motion of the specimens during processing, of course, tends to damage the specimens of carried to excess.
The prior art has also dealt with the problem of heating paraffin fluids in containers, flow lines, valves, and the like. However, no prior art light microscopy processor, so far as is known, has handled this problem successfully by processing the tissue in a closed, effectively sealed system and in a manner enabling the paraffin fluid to be reused. A fluid flow stainer useful only for staining has been marketed by Lipshaw Manufacturing Company of Detroit, Michigan. This apparatus recirculates staining fluids with a pressure-vacuum system applied to the staining fluid containers but it is not useful for processing tissue, does not provide a pressure vessel type chamber, and cannot handle paraffin.
In summary, the prior art in its present state does not embody a practical, reliable and automatic method of processing useful primarily for processing, including use of melted paraffin, but adapted to staining light microscopy tissue specimens with a minimum amount of handling of the tissue specimens, with maximum economy of the treating fluids, and in a closed system which substantially eliminates dangers from hazardous treating fluid fumes.